The present invention relates to the art of filling pressurized containers. It finds particular application in conjunction with injecting paints and lacquers into aerosol cans which have been previously charged with fluid propellants and will be described with particular reference thereto. It is to be appreciated, however, that the present invention may also find application in conjunction with injecting other coating systems, lubricants, fragrances, cleaning agents, and other products commonly sold or dispensed from aerosol cans.
Heretofore, pneumatically operated machines have been available for injecting paint and the like into precharged aerosol cans. As illustrated in U.S. Pat. No. 3,797,534, such devices commonly included a manual lever for lifting an aerosol can to be charged into contact with a relatively small reservoir, e.g. one quart. A pneumatically operated piston drove the paint from a cylinder at the bottom of the reservoir through the aerosol valve into the can.
One of the drawbacks of the prior art machines was that the operator was poorly protected. A tubular frame, at best, has light weight panels attached to the frame. A see-through door which closed over the aerosol can being filled was susceptible to solvent attack. That is, spilled paints adhered to or permanently marred the see-through door rendering it's surface at least partially oblique.
Another disadvantage resided in the location of the operating components. Many of the pneumatic cylinders, control valves, and other moving components were not enclosed within a cabinet. Paint and solvent spilled on these components could damage the controls, by clogging or blocking movement, etching plastic or other solvent sensitive parts, and the like.
Another disadvantage of the prior art resided in the relatively small capacity of the paint reservoir. Moreover, paint within the open topped reservoir tended to lose solvent by evaporation and skin over. The multi-element piston for pumping paint from the reservoir was difficult to position and adjust accurately when reinstalled after cleaning.
The mechanical aerosol can lifting mechanism added an element of potential operator error. If the lever were misadjusted such that the operator could urge the aerosol can against the reservoir too firmly, the aerosol can could be bent or damaged. Such overpressure or analogous underpressure between the can and the reservoir could cause leakage of the paint. During an attempted filling, the paint could spray under pressure over the base and other portions of the filling apparatus. The spilled paint could readily interact with the lever and lift mechanism causing binding and sticking.
The present invention provides a new and improved aerosol can filling apparatus which overcomes the above referenced operator safety and other drawbacks of the prior art.